Novel Grease and Methods of Making the Same

ABSTRACT

The present disclosure relates to a high performance calcium sulfonate greases with enhanced performance benefits and methods for making the same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 15/872,518, filed Jan. 16, 2018, the disclosure of which isincorporated, in its entirety, by this reference.

FIELD OF THE INVENTION

The present invention relates to a high performance calcium sulfonategreases with enhanced performance benefits and methods for making thesame.

BACKGROUND OF THE INVENTION

Overbased calcium sulfonate greases have been an established greasecategory for many years. One known process for making such greases is atwo-step process involving the steps of “promotion” and “conversion.”Typically, the first step (“promotion”) is to react a stoichiometricexcess amount of calcium oxide (CO) or calcium hydroxide (Ca(OH)₂) asthe base source with an alkyl benzene sulfonic acid, carbon dioxide(CO₂), and with other components to produce an oil-soluble overbasedcalcium sulfonate with amorphous calcium carbonate dispersed therein.Typically the second step (“conversion”) is to add a converting agent oragents, such as propylene glycol, isopropyl alcohol, water, formic oracetic acid, to the production of the promotion step, along with asuitable base oil (such as mineral oil), to convert the amorphouscalcium carbonate to a very finely divided dispersion of crystallinecalcium carbonate, also known as a colloidal dispersion, that interactswith the calcium sulfonate to form a grease-like consistency. Suchoverbased calcium sulfonate greases produced through the two-stepprocess have come to be known as “simple calcium sulfonate greases” andare disclosed, for example, in U.S. Pat. Nos. 3,242,079, 3,372,115,3,376,222, 3,377,283 and 3,492,231.

It is also possible to combine the promoting and conversion steps into asingle step by carefully controlling the reaction. In this one-stepprocess, the simple calcium sulfonate grease is prepared by reaction ofan appropriate sulfonic acid with either calcium hydroxide or calciumoxide in the presence of carbon dioxide and a system of reagents thatsimultaneously act as both promoter (creating the amorphous calciumcarbonate overbasing by reaction of carbon dioxide with an excess amountof calcium oxide or calcium hydroxide) and converting agents (convertingthe amorphous calcium carbonate to very finely divided crystallinecalcium carbonate). Thus, the grease-like consistency is formed in asingle step wherein the overbased, oil-soluble calcium sulfonate (theproduct of the first step in the two-step process) is never actuallyformed and isolated as a separate product. One-step processes aredisclosed, for example, in U.S. Pat. Nos. 3,661,622, 3,671,012,3,746,643, and 3,816,310.

In addition to simple calcium sulfonate greases, calcium sulfonatecomplex greases have been prepared. These complex greases are typicallyproduced by adding a strong calcium-containing base, such as calciumhydroxide or calcium oxide, to the simple calcium sulfonate greaseproduced by either the two-step or one-step process, and reacting withstoichiometrically equivalent amounts of complexing acids such as12-hydroxystearic acid (12-HSA), boric acid, acetic acid, or phosphoricacid. Some advantages of calcium sulfonate complex greases over thesimple greases include reduced tackiness, improved pumpability, andimproved high temperature utility. Calcium sulfonate complex greases aredisclosed, for example, in U.S. Pat. Nos. 4,560,489, 5,126,062,5,308,514 and 5,338,467.

Calcium oxide or calcium hydroxide can be used as the source of basiccalcium for production of calcium sulfonate greases or as a requiredcomponent for reacting with complexing acids to form calcium sulfonatecomplex greases. However, the presence of calcium carbonate as aseparate ingredient or as an “impurity” in the calcium hydroxide orcalcium oxide, other than that presence of the amorphous calciumcarbonate dispersed in the calcium sulfonate after carbonation, isundesirable for at least two reasons. The first reason is calciumcarbonate is generally a weak base, unsuitable for reacting withcomplexing acids. The second reason is the presence of unreacted solidcalcium compounds (including calcium hydroxide or calcium oxide)interferes with the conversion process, resulting in inferior greasecompounds if the unreacted solids are not removed prior to conversion orbefore conversion is completed.

It is desirable to have calcium sulfonate complex grease compositionswith worked penetration of National Lubricating Grease Institute (NLGI)categorization 1-3, suitable dropping points for higher temperatureapplications and lower amounts of overbased calcium sulfonate to reducematerial cost. It is further desirable to have methods of manufacturefor such greases that reduce process time and employ open kettlemanufacturing processes to eliminate the need for pressure reactors.

SUMMARY OF THE INVENTION

The present invention provides overbased calcium sulfonate complexgreases that have desirable performance characteristics and improvedmethods for making the same.

One aspect described herein is a complex grease comprising preformedcalcium acetate from about 0.25 wt % to about 5 wt %, an overbasedcalcium sulfonate detergent from about 10 wt % to about 30 wt %, and anoil of lubricating viscosity.

Another aspect described herein is a method for preparing a calciumsulfonate grease comprising the steps of a) providing preformed calciumacetate dissolved in water in a vessel, b) providing an oil oflubricating viscosity to the dissolved preformed calcium acetate inwater in the vessel from step a), c) heating the oil and preformedcalcium acetate mixture of step b), and d) providing an overbasedcalcium sulfonate detergent to the oil and preformed calcium acetatemixture in the vessel from step c).

A third aspect is a grease prepared by one or more of the methodsdescribed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an FTIR spectrum of an embodiment described herein.

FIG. 2 is FTIR spectra of multiple embodiments described herein.

FIG. 3 is FTIR spectra of two embodiments described herein.

FIG. 4 is FTIR spectra of two embodiments described herein.

FIG. 5 is FTIR spectra of comparative compositions relative toembodiments described herein.

DETAILED DESCRIPTION OF THE INVENTION

The invention disclosed herein relates to novel, overbased calciumsulfonate complex greases and improved methods for making the same. Thecomplex greases of the invention have desirable performance propertiesand contain lower amounts of oil-soluble overbased calcium sulfonate ascompared to many prior art greases and, therefore, are economicallyfavorable.

As used herein, the phrase “total base number” or “TBN” refers to thequantity of acid, expressed in terms of the equivalent number ofmilligrams of potassium hydroxide, required to neutralize all basicconstituents present in 1 gram of sample.

As used herein “absorbance intensity” refers to % transmittance as afunction of wavenumber for a particular peak.

As used herein the term “preformed calcium acetate” refers to anhydrous,hemi-hydrated or hydrated calcium acetate in powder form or dissolved inwater, as well as calcium acetate dissolved in water that is preparedfrom a reaction of calcium carbonate or calcium hydroxide with aceticacid, preferably glacial acetic acid, in the absence of a base oil orcarbon dioxide. As used herein, the term “preformed calcium acetate”does not include calcium acetate formed “in situ” during a greasepreparation process, for example, from the reaction of an acid with abasic calcium source, for example a calcium sulfonate detergent, in thepresence of carbon dioxide or a base oil.

As used herein, the term “about” means, with respect to an amount,approximate or almost, and includes the exact amount. For example, thephrase “about 1.0%” means not only approximately or almost 1.0% but alsoincludes exactly 1.0%.

One aspect described herein is a complex calcium sulfonate greasecomprising preformed calcium acetate from about 0.25 wt % to about 5 wt%, an overbased calcium sulfonate detergent from about 10 wt % to about30 wt %, and an oil of lubricating viscosity.

The calcium acetate of the greases of the present invention is preformedcalcium acetate. The amount of preformed calcium acetate in the greaseaccording to the present disclosure is between about 0.1 wt. % to about25 wt. %, between about 0.25 wt. % to about 10 wt. %, between about 0.25wt. % to about 5 wt. % based on the total weight of the grease. In oneembodiment the amount of preformed calcium acetate is between 0.5 wt. %to about 3.5 wt. % based on the total weight of the complex grease.

The grease comprises one or more neutral, overbased calcium sulfonatedetergents. The overbased oil-soluble calcium sulfonate detergent usedaccording to the present disclosure has a TBN value of at least 200, orat least 300, and preferably not more than 400. In one embodiment, theoverbased calcium sulfonate detergent has a TBN of from about 300 toabout 400. Commercially available overbased calcium sulfonate detergentsof this type include but are not limited to, the following: HiTEC 611®as supplied by Afton Chemical, Hybase C401 as supplied by Chemtura USACorporation, and Syncal OB 400 and Syncal OB405-WO as supplied by KimesTechnologies International Corporation, and LZ 5358, a 400 TBN detergentas supplied by Lubrizol.

The amount of the overbased oil-soluble calcium sulfonate detergent inthe final grease according to the present disclosure can vary, but willgenerally be between about 5 wt. % to about 30 wt. %, between about 10wt. % to about 30 wt. % based on the total weight of the grease. In oneembodiment, the amount of overbased calcium sulfonate detergent isbetween about 20 wt. % to about 30 wt. % based on the total weight ofthe grease.

In one embodiment, the range of the ratio of preformed calcium acetateto overbased calcium sulfonate detergent is from about 1:2 to about1:100. In another embodiment, the range of the ratio of preformedcalcium acetate to calcium sulfonate is about 1:5 to about 1:55.

The greases of the present disclosure comprise at least one oil oflubricating viscosity or base oil. As used herein, the term “oil oflubricating viscosity”, “base oil” or “base stock” refers to oilscategorized by the American Petroleum Institute (API) category groupsGroup I-V oils as well as animal oils, vegetable oils (e.g. castor oiland lard oil), petroleum oils, mineral oils, synthetic oils, and oilsderived from coal or shale. The American Petroleum Institute hascategorized these different base stock types as follows: Group I,greater than 0.03 wt percent sulfur, and/or less than 90 vol percentsaturates, viscosity index greater than or equal to 80 and less than120; Group II, less than or equal to 0.03 wt percent sulfur, and greaterthan or equal to 90 vol percent saturates, viscosity index greater thanor equal to 80 and 120; Group III, less than or equal to 0.03 wt percentsulfur, and greater than or equal to 90 vol percent saturates, viscosityindex greater than or equal to 120; Group IV, all polyalphaolefins;Group V base stock encompasses all other base stocks which cannot beclassified as Group I, II, III, or IV base stocks. Group V base stocksinclude but are not limited to naphthenic oils and esters. Hydrotreatedbase stocks and catalytically dewaxed base stocks, because of their lowsulfur and aromatics content, generally fall into the Group II and GroupIII categories. Polyalphaolefins (Group IV basestocks) are syntheticbase oils prepared from various alpha olefins and are substantially freeof sulfur and aromatics.

Groups I, II, and III are mineral oil process stocks. Group IV base oilscontain true synthetic molecular species, which are produced bypolymerization of olefinically unsaturated hydrocarbons. Many Group Vbase oils are also true synthetic products and may include diesters,polyol esters, polyalkylene glycols, alkylated aromatics, polyphosphateesters, polyvinyl ethers, and/or polyphenyl ethers, and the like, butmay also be naturally occurring oils, such as vegetable oils. It shouldbe noted that although Group III base oils are derived from mineral oil,the rigorous processing that these fluids undergo causes their physicalproperties to be very similar to some true synthetics, such as PAOs.Therefore, oils derived from Group III base oils may sometimes bereferred to as synthetic fluids in the industry. In an embodiment of thepresent invention, the base oil is an oil selected from Groups I, II,III IV and V. In certain embodiments, the base oil is a mixture of oneor more oils selected from Groups I, II, III, IV and V. Mixtures of baseoils include mixtures of two or more base oils from the same group, twoor more base oils from different groups, and any number of base oilsfrom any of Groups I, II, III, IV and V.

The amount of base oil or oil of lubricating viscosity in the finalgrease according to the present disclosure may vary broadly, but willgenerally comprise from about 5 wt % to about 95 wt % based on the totalweight of the grease. In one embodiment, the base oil will comprise fromabout 15% wt % to about 60 wt %.

In one embodiment, the grease further comprises one or more complexingacids. In some embodiments, the grease comprises at least two complexingacids. Complexing acids comprise at least one or more long chaincarboxylic acids, short chain carboxylic acids, boric acid, phosphoricacid or sulfonic acid. Long chain carboxylic acids suitable for useaccording to the present disclosure comprise aliphatic carboxylic acidswith at least 16 carbon atoms and include 12-hydroxystearic acid(12-HSA) and are present from about 0.5 wt % to about 5 wt % based onthe final weight of the grease. Short chain carboxylic acids suitablefor greases of the present disclosure comprise aliphatic carboxylicacids with no more than 8 carbon atoms, and preferably no more than 4atoms. In one embodiment, the short chain carboxylic acid is aceticacid. In another embodiment, short chain carboxylic acids are presentfrom about 0.5 wt % to about 2 wt % based on the final weight of thegrease.

Boric acid may be used as a complexing acid according to the presentdisclosure, in an amount from about 0.4 wt % to about 4 wt % based onthe final weight of the grease. The boric acid may be added after firstbeing dissolved or slurried in water, or it can be added without water.Preferably, the boric acid is added during the manufacturing processsuch that water is still present. Alternatively, any of the well-knowninorganic boric acid salts may be used instead of boric acid. Likewise,any of the established borated organic compounds such as borated amines,borated amides, borated esters, borated alcohols, borated glycols,borated ethers, borated epoxides, borated ureas, borated carboxylicacids, borated sulfonic acids, borated expoxides, borated peroxides andthe like may be used instead of boric acid. If phosphoric acid acid isused as a complexing agent, it is used in an amount from about 0.4 wt %to about 4 wt % based on the final weight of the grease.

The complexing acid may also be alkyl benzene sulfonic acid, having analkyl chain lengthy typically between about 1 to 20 carbons, which mayhelp to facilitate efficient grease structure formation. In oneembodiment, the alkyl benzene sulfonic acid comprises a mixture of alkylchain lengths that are mostly about 12 carbons in length. In oneembodiment, the benzene sulfonic acid is dodecylbenzene sulfonic acid(“DDBSA”). Commercially available benzene sulfonic acids of this typeinclude JemPak 1298 Sulfonic Acid as supplied by JemPak GK Inc., CalsoftLAS-99 as supplied by Pilot Chemical Company, and Biosoft S-101 assupplied by Stepan Chemical Company. When the alkyl benzene sulfonicacid is used as described in the present disclosure, it is added in anamount from about 0.5 wt % to about 5 wt % based on the final weight ofthe grease.

The percentages of various complexing acids described herein refer topure, active compounds. If any of these complexing acids are availablein a diluted form, they may still be suitable for use in the presentinvention. However, the percentages of such diluted complexing acidswill need to be adjusted so as to take into account the dilution factorand bring the actual active material into the specified percentageranges.

The grease of the present disclosure may further comprise one or moreconverting agents, such as alcohols, ethers, glycols, glycol ethers,glycol polyethers, carboxylic acids, inorganic acids, organic nitrates,and any other compounds that contain either active or tautomerichydrogen. The converting agents are used in an amount from about 0.1 wt% to about 5 wt % based on the final weight of the grease. Depending onthe converting agents used, they may be removed by volatilization duringthe manufacturing process. In one embodiment the complexing agent is analcohol. In another embodiment, the complexing agent is selected fromisopropyl alcohol and ethoxy ethanol. In one embodiment, the complexingagent is 2-ethoxyethanol.

The grease of the present disclosure may further comprise additionallubricant performance additives. The additives include, but not limitedto, antioxidants, metal deactivators, metal passivators, chelatingagents, polymers, chemical markers, fragrance imparters, evaporativesolvents, antiscuffing agents, foam inhibitors, demulsifiers, frictionmodifiers, corrosion inhibitors, antiwear agents, pour pointdepressants, tackiness agents, extreme pressure agents, viscositymodifiers, oxidation inhibitors, rust inhibitors, dyes and like. Suchcomponents may be present in the fully formulated grease composition inamount ranging from about 1 wt. % to about 10 wt. % based on the finalweight of the composition.

Antioxidants

Antioxidant compounds are known and include, for example, phenates,phenate sulfides, sulfurized olefins, phosphosulfurized terpenes,sulfurized esters, aromatic amines, alkylated diphenylamines (e.g.,nonyl diphenylamine, di-nonyl diphenylamine, octyl diphenylamine,di-octyl diphenylamine), phenyl-alpha-naphthylamines, alkylatedphenyl-alpha-naphthylamines, hindered non-aromatic amines, phenols,hindered phenols, oil-soluble molybdenum compounds, macromolecularantioxidants, or mixtures thereof. A single antioxidant or a combinationof two or more can be used.

The hindered phenol antioxidant may contain a secondary butyl and/or atertiary butyl group as a sterically hindering group. The phenol groupmay be further substituted with a hydrocarbyl group and/or a bridginggroup linking to a second aromatic group. Examples of suitable hinderedphenol antioxidants include 2,6-di-tert-butylphenol,4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol,4-propyl-2,6-di-tert-butylphenol or 4-butyl-2,6-di-tert-butylphenol, or4-dodecyl-2,6-di-tert-butylphenol. In an embodiment the hindered phenolantioxidant may be an ester and may include, e.g., an addition productderived from 2,6-di-tert-butylphenol and an alkyl acrylate, wherein thealkyl group may contain about 1 to about 18, or about 2 to about 12, orabout 2 to about 8, or about 2 to about 6, or about 4 carbon atoms.

Useful antioxidants may include diarylamines and high molecular weightphenols. In an embodiment, the grease composition may contain a mixtureof a diarylamine and a high molecular weight phenol, such that eachantioxidant may be present in an amount sufficient to provide up toabout 5%, by weight of the antioxidant, based upon the final weight ofthe grease composition. In some embodiments, the antioxidant may be amixture of about 0.3 to about 1.5% diarylamine and about 0.4 to about2.5% high molecular weight phenol, by weight, based upon the finalweight of the grease composition.

Examples of suitable olefins that may be sulfurized to form a sulfurizedolefin include propylene, butylene, isobutylene, polyisobutylene,pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene,tridecene, tetradecene, pentadecene, hexadecene, heptadecene,octadecene, nonadecene, eicosene or mixtures thereof. In an embodiment,hexadecene, heptadecene, octadecene, nonadecene, eicosene or mixturesthereof and their dimers, trimers and tetramers are especially usefulolefins. Alternatively, the olefin may be a Diels-Alder adduct of adiene such as 1,3-butadiene and an unsaturated ester, such as,butylacrylate.

Another class of sulfurized olefin includes sulfurized fatty acids andtheir esters. The fatty acids are often obtained from vegetable oil oranimal oil and typically contain about 4 to about 22 carbon atoms.Examples of suitable fatty acids and their esters include triglycerides,oleic acid, linoleic acid, palmitoleic acid or mixtures thereof. Often,the fatty acids are obtained from lard oil, tall oil, peanut oil,soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof.Fatty acids and/or ester may be mixed with olefins, such as α-olefins.

The one or more antioxidant(s) may be present in ranges of from about 0wt. % to about 20 wt. %, or about 0.1 wt. % to about 10 wt. %, or about1 wt. % to about 5 wt. %, of the lubricating composition.

Antiwear Agents

The grease composition of the present disclosure may comprise antiwearagents. Examples of suitable antiwear agents include, but are notlimited to, a metal thiophosphate; a metal dialkyldithiophosphate; aphosphoric acid ester or salt thereof; a phosphate ester(s); aphosphite; a phosphorus-containing carboxylic ester, ether, or amide; asulfurized olefin; thiocarbamate-containing compounds including,thiocarbamate esters, alkylene-coupled thiocarbamates, andbis(S-alkyldithiocarbamyl)disulfides; and mixtures thereof. Thephosphorus containing antiwear agents are more fully described inEuropean Patent No. 1490460. The metal in the dialkyl dithio phosphatesalts may be an alkali metal, alkaline earth metal, aluminum, lead, tin,molybdenum, manganese, nickel, copper, titanium, or zinc. A usefulantiwear agent may be a thiophosphate such as zincdialkyldithiophosphate.

The antiwear agent may be present in ranges of from about 0 wt. % toabout 15 wt. %, or about 0.01 wt. % to about 10 wt .%, or about 0.05 wt.% to about 5 wt. %, or about 0.1 wt. % to about 3 wt. % of the totalweight of the grease composition. In certain embodiments, the additionalantiwear agent(s) are in the form of amine salts and present in lessthan or equal to about 1.0 wt %, less than or equal to about 0.5 wt % orless than or equal to about 0.25 wt %. In other embodiments, theadditional antiwear agents are not amine salts.

Extreme Pressure Agents

The grease composition herein also may optionally contain one or moreextreme pressure agents. Extreme Pressure (EP) agents that are solublein the oil include sulfur- and chlorosulfur-containing EP agents,chlorinated hydrocarbon EP agents and phosphorus EP agents. Examples ofsuch EP agents include chlorinated waxes; organic sulfides andpolysulfides such as dibenzyldisulfide, bis(chlorobenzyl) disulfide,dibutyl tetrasulfide, sulfurized methyl ester of oleic acid, sulfurizedalkylphenol, sulfurized dipentene, sulfurized terpene, and sulfurizedDiels-Alder adducts; phosphosulfurized hydrocarbons such as the reactionproduct of phosphorus sulfide with turpentine or methyl oleate;phosphorus esters such as the dihydrocarbyl and trihydrocarbylphosphites, e.g., dibutyl phosphite, diheptyl phosphite, dicyclohexylphosphite, pentylphenyl phosphite; dipentylphenyl phosphite, tridecylphosphite, distearyl phosphite and polypropylene substituted phenylphosphite; metal thiocarbamates such as zinc dioctyldithiocarbamate andbarium heptylphenol diacid; amine salts of alkyl and dialkylphosphoricacids, including, for example, the amine salt of the reaction product ofa dialkyldithiophosphoric acid with propylene oxide; and mixturesthereof.

In one embodiment, the organic polysulfides are S-3 enriched organicpolysulfides. As used herein, the phrase “S-3 enriched organicpolysulfides” refers to organic polysulfides that contain moretrisulfide species than mono-sulfide or other polysulfide species. Insome embodiments, the S-3 enriched organic polysulfides contain at least50 wt % trisulfides, or at least 55%, at least 60%, at least 65%, atleast 75% or at least 80% trisulfides, with the remaining organicpolysulfides being primarily S-2 and S-4 polysulfides. In certainembodiments, the S-3 enriched organic polysulfides contain almost 100%trisulfides. In some embodiments, the molar ratios of S-2:S-3:S-4polysulfides are from about 10-30:50-80:10-30. In certain embodiments,the S-3 enriched organic polysulfides have hydrocarbyl groups eachindependently having from about 2 to about 30 carbons or from about 2 toabout 20 carbons, or from about 2 to about 12 carbons or from about 3 toabout 6 carbons. The hydrocarbyl groups can be aromatic or aliphatic,but are preferably aliphatic. In certain embodiments, the hydrocarbylgroups are alkyl groups. In one embodiment, the S-3 enriched organicpolysulfides comprise at least 60% dihydrocarbyl trisulfide. In otherembodiments, the organic polysulfides by weight % of the totalpolysulfides are from about 5 wt % to about 20 weight % S-2; from about30 wt % to about 80 wt % S-3, and from about 5 wt % to about 50 wt %S-4. Examples of suitable S-3 enriched organic polysulfides includethose disclosed in U.S. Pat. Nos. 6,642,187, 6,689,723, or 6,489,271.

Friction Modifiers

The grease composition herein may also optionally contain one or moreadditional friction modifiers. Suitable friction modifiers may comprisemetal containing and metal-free friction modifiers and may include, butare not limited to, imidazolines, amides, amines, succinimides,alkoxylated amines, alkoxylated ether amines, amine oxides, amidoamines,nitriles, betaines, quaternary amines, imines, amine salts, aminoguanidines, alkanolamides, phosphonates, metal-containing compounds,glycerol esters, sulfurized fatty compounds and olefins, sunflower oiland other naturally occurring plant or animal oils, dicarboxylic acidesters, esters or partial esters of a polyol and one or more aliphaticor aromatic carboxylic acids, and the like.

Suitable friction modifiers may contain hydrocarbyl groups that areselected from straight chain, branched chain, or aromatic hydrocarbylgroups or mixtures thereof, and may be saturated or unsaturated. Thehydrocarbyl groups may be composed of carbon and hydrogen or heteroatoms such as sulfur or oxygen. The hydrocarbyl groups may range fromabout 12 to about 25 carbon atoms. In a embodiments the frictionmodifier may be a long chain fatty acid ester. In an embodiment the longchain fatty acid ester may be a mono-ester, or a di-ester, or a(tri)glyceride. The friction modifier may be a long chain fatty amide, along chain fatty ester, a long chain fatty epoxide derivative, or a longchain imidazoline.

Other suitable friction modifiers may include organic, ashless(metal-free), nitrogen-free organic friction modifiers. Such frictionmodifiers may include esters formed by reacting carboxylic acids andanhydrides with alkanols and generally include a polar terminal group(e.g. carboxyl or hydroxyl) covalently bonded to an oleophilichydrocarbon chain. An example of an organic ashless nitrogen-freefriction modifier is known generally as glycerol monooleate (GMO) whichmay contain mono-, di-, and tri-esters of oleic acid. Other suitablefriction modifiers are described in U.S. Pat. No. 6,723,685.

Aminic friction modifiers may include amines or polyamines. Suchcompounds can have hydrocarbyl groups that are linear, either saturatedor unsaturated, or a mixture thereof and may contain from about 12 toabout 25 carbon atoms. Further examples of suitable friction modifiersinclude alkoxylated amines and alkoxylated ether amines. Such compoundsmay have hydrocarbyl groups that are linear, either saturated,unsaturated, or a mixture thereof. They may contain from about 12 toabout 25 carbon atoms. Examples include ethoxylated amines andethoxylated ether amines.

The amines and amides may be used as such or in the form of an adduct orreaction product with a boron compound such as a boric oxide, boronhalide, metaborate, boric acid or a mono-, di- or tri-alkyl borate.Other suitable friction modifiers are described in U.S. Pat. No.6,300,291.

A friction modifier may be present in amounts of about 0 wt. % to about10 wt. %, or about 0.01 wt. % to about 8 wt. %, or about 0.1 wt. % toabout 4 wt. %, based on the total weight of the grease composition.

Viscosity Index Improvers

The grease composition herein also may optionally contain one or moreviscosity index improvers. Suitable viscosity index improvers mayinclude polyolefins, olefin copolymers, ethylene/propylene copolymers,polyisobutenes, hydrogenated styrene-isoprene polymers, styrene/maleicester copolymers, hydrogenated styrene/butadiene copolymers,hydrogenated isoprene polymers, alpha-olefin maleic anhydridecopolymers, polymethacrylates, polyacrylates, polyalkyl styrenes,hydrogenated alkenyl aryl conjugated diene copolymers, or mixturesthereof. Viscosity index improvers may include star polymers andsuitable examples are described in US Publication No. 2012/0101017 A1.

The grease composition herein also may optionally contain one or moredispersant viscosity index improvers in addition to a viscosity indeximprover or in lieu of a viscosity index improver. Suitable dispersantviscosity index improvers may include functionalized polyolefins, forexample, ethylene-propylene copolymers that have been functionalizedwith the reaction product of an acylating agent (such as maleicanhydride) and an amine; polymethacrylates functionalized with an amine,or esterified maleic anhydride-styrene copolymers reacted with an amine.

The total amount of viscosity index improver and/or dispersant viscosityindex improver may be about 0 wt. % to about 20 wt. %, about 0.1 wt. %to about 15 wt. %, about 0.1 wt. % to about 12 wt. %, or about 0.5 wt. %to about 10 wt. % based on the total weight, of the lubricatingcomposition.

Effective amounts of the various additive components for a specificformulation may be readily ascertained, but for illustrative purposesthese general guides for representative effective amounts are provided.The amounts below are given in weight % of the finished fluid.

Methods of Making Grease

One aspect of the invention described herein is a method for preparing acalcium sulfonate grease comprising the steps of a) providing preformedcalcium acetate dissolved in water in a vessel, b) providing an oil oflubricating viscosity to the dissolved preformed calcium acetate inwater in the vessel from step a), c) heating the oil and preformedcalcium acetate mixture of step b), and d) providing overbased calciumsulfonate detergent to the oil and preformed calcium acetate mixture inthe vessel from step c). In one embodiment, the method is forpreparation of a simple grease. In another embodiment, the method is forpreparation of a complex grease.

This method may occur in either an open or closed kettle as is commonlyused for grease manufacturing. The process can be achieved at normalatmospheric pressure although can be carried out under pressure in aclosed kettle. In one embodiment, the method is carried out in openkettles.

In one embodiment the method further comprises e) adding one or morecomplexing acids to the mixture of step d), and f) adding one or moreconverting agents to the mixture of step e). In some embodiments, two ormore of steps a) through f) of the method are performed in order. Inanother embodiment, all of steps a) through f) are performed in order.

In one embodiment, the preformed calcium acetate used in the method is acalcium acetate powder dissolved in water. In another embodiment, theamounts of calcium acetate powder and water are about one part calciumacetate powder dissolved in about ten parts water. In anotherembodiment, the preformed calcium acetate is prepared from a basiccalcium source and an acid prior to the addition of any base oil.

In one embodiment, the greases of the present invention have theconsistency of common greases as classified by the National LubricatingGrease Institute (NLGI). Common greases have NLGI categorization of 1-3,corresponding to a penetration of about 230 to about 340 as measured byASTM D217. In certain embodiments, the grease is a complex grease with apenetration of about 230 to about 340 as measured by ASTM D217. In otherembodiments, the complex grease has a penetration of from about 265 toabout 295 as measured by ASTM D217.

As understood by the skilled artisan, the simple greases describedherein may be used to form complex greases with the addition ofsaponification agents, such as lime, complexing acids, such as 12-HSA,and additional base oil. The complex greases prepared from the simplegreases will generally have somewhat higher penetration scores than thesimple greases from which they are prepared due to the additional volumeof base oil and additional components, but will maintain the desireddropping point. The higher penetration scores of the complex greases arestill within NLGI categories 1-3, and in certain embodiments are in NLGIcategory 2.

The dropping point of a lubricating grease is an indication of the heatresistance of the grease and is the temperature at which it passes froma semi-solid to a liquid state under specific test conditions. Thedropping point indicates the upper temperature limit at which a greaseretains its structure though is not necessarily the maximum temperatureat which a grease can be used. In one embodiment, the complex grease ofthe invention has a dropping point of from about 250° C. to about 400°C. as measured by ASTM D2265.

The composition of greases can be characterized by Fourier transformedinfrared (FTIR) spectroscopy. In one embodiment, infrared spectra of thegreases of the instant invention comprise an absorbance peak at 1569cm⁻¹±1. In another embodiment, the infrared spectra of the greasesfurther comprises an absorbance peak at 883 cm⁻¹±1. The presence of apeak at about 1569 cm⁻¹ is characteristic of a carbonyl peak anddemonstrates incorporation of calcium acetate into the grease structurewith relative intensity of the peaks corresponding to relative calciumacetate content of each batch. The presence of a peak at about 883 cm⁻¹is characteristic of a calcite peak and demonstrates the presence of acalcite allotrope of CaCO3.

The relationship of peak intensity (percent transmission or % T) of thecharacteristic carbonyl peak at 1569 cm⁻¹±1 and the grease penetrationas measured by ASTM D217 is generally a linear relationship. In certainembodiments, the ratio of peak intensity (% T) at 1569±1 to penetrationas measured by ASTM D217 is from about 1:2.4 to about 1:3.4.

Although certain embodiments of the present disclosure may be describedindividually herein, it is understood by the skilled artisan that anyone embodiment can be combined with any other embodiment or embodiments,and such combinations are within the scope of the instant disclosure.

EXAMPLES Example 1 Preparation of Batch 1 Complex Grease CompositionUsing Preformed Anhydrous Calcium Acetate

Calcium sulfonate complex greases are prepared as described in Table 1as Batch 1 using the following procedure: Anhydrous calcium acetate (AVAChemical Pvt Ltd, Mumbai, Maharashtra—CAS Number-62-54-4: 5743-26-0) isplaced in an open mixing vessel. Water (approximately 10× of the amountof calcium acetate) is added to the vessel to completely disperse thecalcium acetate. Base oil (20% of the total amount) is added to thevessel containing the calcium acetate solution and the mixture is heatedto a temperature of 80° C. Calcium sulfonate (Afton Chemical—HiTEC® 611,307 TBN) is added to the vessel with stirring and the mixture ismaintained at a temperature of approximately 85° C.

Dodecyl benzene sulfonic acid (Afton Chemical—HiTEC® 052) is added withstirring until the material becomes viscous. 2-ethoxy-ethanol (LabortFinechem Pvt Ltd, Gujarat—CAS Number 110-80-5) is added with mixing andthe temperature is maintained at approximately 90-95° C. The mixture isstirred continuously for approximately 1.5-2.0 hours at approximately90-95° C. The mass is observed and the mixture is stirred until themixture becomes transparent. The process of converting amorphous calciumcarbonate to crystalline calcite can be monitored either by visualappearance or by FT-IR spectroscopy. Amorphous calcium carbonate absorbsat 863 cm⁻¹. Calcite absorbs at 883-884 cm⁻¹. Up to half of theremaining base oil is added if needed to achieve the desired transparentmixture.

The mixture is slowly (30-45 minutes) heated to 125° C. Lime and aminimal amount of water is stirred in a separate vessel to form aslurry. The lime/water slurry is added slowly to the main vessel withstirring. The mixture is heated to return the temperature of the mixtureto approximately 125-130° C. 12-hydroxystearic acid (12 HSA) is addedwith stirring until the mixture becomes thick and the thickened mixtureis heated to 140° C. Small amounts of water are added as needed tocomplete the saponification of the 12-hydroxystearic acid. The mixtureis slowly heated to approximately 180-185° C. The temperature of themixture is held at approximately 180-185° C. for about 10 minutes andthen cooled to around 130° C. The remaining base oil is added withstirring to achieve the desire consistency and the grease mixture iscooled completely.

The grease is passed through a vertical colloidal milling machine (with0.1 mm clearance) for single pass to achieve a final smooth homogenoustexture. Fourier Transform Infrared Spectroscopy (FT-IR) is performed onBatch 1 and yielded infrared spectra according to FIG. 1. Dropping point(ASTM D2265), penetration (ASTM D217), four ball weld load (IP239), wearscar diameter (ASTM D2266) and reaction time to form a grease isdetermined for each grease batch. The results are summarized in Table 2.

Example 2 Preparation of Batches 2-6 Simple Grease Compositions UsingPreformed Anhydrous Calcium Acetate

Simple calcium sulfonate greases, Batches 2-6, are prepared as describedin Table 1 using the procedure of Example 1, except the complexingagent, 12 HSA, and lime are not added during grease formation. Theseexperiments are carried out to see the effect of using preformed calciumacetate during the formation of simple calcium sulfonate greases.

Results are shown in Table 4.

TABLE 1 Component (parts)* Batch 1 Batch 2 Batch 3 Batch 4 Batch 5 Batch6 Calcium 1.5 0.5 1 1.5 2 3 acetate Overbased 26 26 26 26 26 26 calciumsulfonate detergent Dodecyl 2.5 2.5 2.5 2.5 2.5 2.5 benzenesulfonicsulfonic acid 2-Ethoxy 2.0 2.0 2.0 2.0 2.0 2.0 Ethanol Lime 1.012 HSA 5.0 Total Ca 4.25 3.21 3.33 3.45 3.58 3.84 amount in final greaseBase Oil 62 20 20 20 20 20 Brightstock- 150 *All components are listedin parts for ease of comparison of the amount of calcium acetate in thecomplex grease (Batch 1) versus the simple greases (Batches 2-6).Batches 2-6 can be used to form complex greases, for example, with theaddition of lime, 12 HSA and the balance base oil.

TABLE 2 Performance characteristics Batch 1 Batch 2 Batch 3 Batch 4Batch 5 Batch 6 Drop point 296 >380 >380 >320 333 320 (° C.) Penetrationx 287 327 318 256 237 230 60 Weld load 315 225 225 250 355 400 (kgf) WSD(mm) 0.51 0.52 0.54 0.52 0.46 0.43 Reaction time 480 90 90 90 90 90 toform grease (minutes)

Fourier Transform Infrared Spectroscopy was performed on Examples 2-6and yielded infra-red spectra according to FIG. 2. As shown in FIG. 2,Batches 2-6 had a characteristic carbonyl peak at ˜1569 cm⁻¹demonstrating incorporation of calcium acetate into the grease structurewith relative intensity of the peaks corresponding to relative calciumacetate content of each batch. All batches also had a characteristiccalcite peak at 883-884 cm⁻¹ demonstrating the presence of the calciteallotrope of CaCO₃. The ratio of peak intensity to penetration scoresuggests a linear relationship. The results are summarized in Table 3.

TABLE 3 Components Batch 2 Batch 3 Batch 4 Batch 5 Batch 6 Ratio ofcalcium 1:52 1:26 1:17 1:13 1:7 acetate to overbased calcium sulfonatedetergent Peak intensity (% T) 95 93 92 91 89 Ratio of peak 1:3.4 1:3.41:2.8 1:2.6 1:2.6 intensity to penetration (ASTM D217)

Example 3 Preparation of Simple Calcium Sulfonate Greases Prepared UsingPerformed Calcium Acetate Prepared Prior to the Addition of Base Oil

Batch 7 is prepared according to Table 4 using the procedure of Example2, except that instead of placing anhydrous calcium acetate in thevessel and dissolving it in water, finely divided calcium carbonate witha mean particle size below 5 microns (Riddhi Chemicals, Mumbai,Maharashtra—CAS Number-471-34-1) is added to the mixing vessel. Water(approximately 5× of the amount of calcium carbonate) is added to thevessel to completely disperse the calcium carbonate and this mixture ismixed with glacial acetic acid (Riddhi Chemicals, Mumbai,Maharashtra—CAS Number-64-19-7) in the vessel prior to adding the baseoil.

Batch 8 is prepared according to Table 4 using the procedure of Example1, except that instead of placing anhydrous calcium acetate in thevessel and dissolving it in water, finely divided food grade puritycalcium hydroxide base with a mean particle size of about 4 microns(Riddhi Chemicals, Mumbai, Maharashtra—CAS Number-1305-62-0) is added tothe mixing vessel. Water (approximately 5× of the amount of calciumhydroxide) is added to the vessel to completely disperse the calciumhydroxide and this mixture is mixed with glacial acetic acid in thevessel prior to adding the base oil.

The results of Batches 7 and 8 are shown in Table 5.

TABLE 4 Components (parts) Batch 7 Batch 8 Calcium carbonate 2.0 Calciumhydroxide 0.70 Glacial acetic acid 2.5 1.14 Overbased calcium sulfonatedetergent 26 26 Dodecyl benzene sulfonic acid 2.5 2.5 2-ethoxy-ethanol2.0 2.0 Total Ca amount in final grease 3.88 3.46 Base Oil 20 20Brightstock-150 Calcium acetate formed 3 1.5

TABLE 5 Performance characteristics Batch 7 Batch 8 Drop point (° C.)304 306 Penetration × 60 223 266 Weld load (kgf) 500 250 WSD (mm) 0.410.52 Reaction time 180 120 (minutes)

Fourier Transform Infrared Spectroscopy of Batch 7 and Batch 8 yieldedIR spectra according to FIG. 3. A comparison of Batch 4 and Batch 8shows identical infra-red spectra with both the characteristic carbonylpeak at ˜1569 cm⁻¹, and the characteristic calcite peak at 883-884 cm⁻¹as shown in FIG. 4.

Example 4 (Comparative)

Simple calcium sulfonate greases, Batches 9 and 10, are preparedaccording to Table 6 using the procedure of Example 2, except thatinstead of placing anhydrous calcium acetate in the vessel anddissolving it in water, water alone (Batch 9) or water and glacialacetic acid (Batch 10) are placed in the vessel and mixed with the baseoil.

As shown in Table 7, the grease produced by this method exhibited higherreaction times, lower dropping points and higher penetration scores ascompared to the greases of the invention.

TABLE 6 Components (wt %) Batch 9 Batch 10 Glacial acetic acid — 1.14Overbased calcium sulfonate 26.0 26.0 detergent Dodecyl benzene sulfonicacid 2.5 2.5 2-ethoxy-ethanol 2.0 2.0 Total Ca amount in final grease3.08 3.08 Base Oil 20 20 Brightstock-150 Theoretical calcium acetate —1.5 formed

TABLE 7 Performance characteristics Batch 9 Batch 10 Drop point (° C.)290   302   Penetration × 60 463   369   Weld load (kgf) 225   250   WSD(mm)  0.53  0.51 Reaction time (minutes) 120+   120+  

Fourier Transform Infrared Spectroscopy of Batches 9 and 10 yielded IRspectra according to FIG. 5.

What is claimed is:
 1. A complex grease comprising: preformed calciumacetate from about 0.25 wt % to about 5 wt %; an overbased calciumsulphonate detergent from about 10 wt % to about 30 wt %; and an oil oflubricating viscosity.
 2. The complex grease of claim 1, wherein thecomplex grease has a penetration of about 230 to about 340 as measuredby ASTM D217.
 3. The complex grease of claim 1, wherein the complexgrease has a drop point of from about 250° C. to about 400° C.
 4. Thecomplex grease of claim 1, wherein an infrared spectrum of the greasecomprises an absorbance peak at 1569 cm⁻¹±1.
 5. The complex grease ofclaim 4, wherein the infrared spectrum of the grease further comprisesand an absorbance peak at 883 cm⁻¹±1.
 6. The complex grease of claim 1,wherein the ratio of preformed calcium acetate to overbased calciumsulphonate detergent is from about 1:2 to about 1:100.
 7. The complexgrease of claim 1, wherein the ratio of peak intensity (% T) of theabsorbance peak at 1569 cm⁻¹±1 to grease penetration measured by ASTMD217 is from about 1:2.4 to about 1:3.4.
 8. The complex grease of claim1, wherein the preformed calcium acetate is from about 0.5 wt % to about3.5 wt %.
 9. The complex grease of claim 1, wherein the overbasedcalcium sulphonate detergent is from about 20 wt % to about 30 wt %. 10.The complex grease of claim 1, wherein the oil of lubricating viscosityis selected from the group consisting of group I, group II, group III,group IV and group V oils, or is selected from a mixture of one or moreoils of group I, group II, group III, group IV and group V base oils.11. The complex grease of claim 1, wherein the overbased calciumsulphonate detergent has a total base number (TBN) from about 300 toabout
 400. 12. The complex grease of claim 1, wherein the complex greasefurther comprises one or more complexing acids selected from the groupconsisting of a long chain carboxylic acid, a short chain carboxylicacid, boric acid, phosphoric acid, and alkyl benzene sulphonic acid. 13.The complex grease of claim 12, wherein at least one of the complexingacids is C₁-C₂₀ alkyl benzene sulphonic acid.
 14. The complex grease ofclaim 13, wherein the C₁-C₂₀ alkyl benzene sulphonic acid isdodecylbenzene sulfonic acid.
 15. The complex grease of claim 12,wherein the complex grease comprises at least two complexing acids. 16.The complex grease of claim 15, wherein the at least two complexingacids comprise dodecylbenzene sulfonic acid and 12-hydroxystearic acid.17. The complex grease of claim 1, wherein the complex grease furthercomprises one or more converting agents selected from the groupconsisting of alcohols, ethers, glycols, glycol ethers, glycolpolyethers, carboxylic acids, inorganic acids, organic nitrates,compounds that contain active hydrogen, and compounds that containtautomeric hydrogen.
 18. The complex grease of claim 1, wherein thecomplex grease further comprises one or more additives selected from thegroup consisting of antioxidants, rust inhibitors, metal deactivators,antiwear agents, antiscuffing agents, extreme pressure agents, foaminhibitors, demulsifiers, friction modifiers, viscosity modifiers, andpour point depressants.
 19. A calcium sulfonate grease preparedaccording to the steps of: a) providing preformed calcium acetatedissolved in water in a vessel; b) providing an oil of lubricatingviscosity to the dissolved preformed calcium acetate in water in thevessel from step a), c) heating the oil and preformed calcium acetatemixture of step b); and d) providing an overbased calcium sulfonatedetergent to the oil and preformed calcium acetate mixture in the vesselfrom step c).
 20. The grease according to claim 19, wherein an infraredspectrum of the grease comprises an absorbance peak at 1569 cm⁻¹±1 and883 cm⁻¹±1.